Earth's magnetic field has started to weaken

Washington, July 1 : A new study has determined that rapid changes in the churning movement of Earth's liquid outer core are weakening the magnetic field in some regions of the planet's surface.

"What is so surprising is that rapid, almost sudden, changes take place in the Earth's magnetic field," said study co-author Nils Olsen, a geophysicist at the Danish National Space Center in Copenhagen.

According to a report in National Geographic News, the findings suggest similarly quick changes are simultaneously occurring in the liquid metal, 1,900 miles (3,000 kilometers) below the surface.

The swirling flow of molten iron and nickel around Earth's solid center triggers an electrical current, which generates the planet's magnetic field.

The study modeled Earth's magnetic field using nine years of highly accurate satellite data.

The researchers found that fluctuations in the magnetic field have occurred in several far-flung regions of Earth.

In 2003, scientists found pronounced changes in the magnetic field in the Australasian region. In 2004, however, the changes were focused on Southern Africa.

"The changes may suggest the possibility of an upcoming reversal of the geomagnetic field," said study co-author Mioara Mandea, a scientist at the German Research Centre for Geosciences in Potsdam.

Earth's magnetic field has reversed hundreds of times over the past billion years, and the process could take thousands of years to complete.

The decline in the magnetic field also is opening Earth's upper atmosphere to intense charged particle radiation, according to scientists.

Satellite data show the geomagnetic field decreasing in the South Atlantic region, said Mandea, adding that an oval-shaped area east of Brazil is significantly weaker than similar latitudes in other parts of the world.

"It is in this region that the shielding effect of the magnetic field is severely reduced, thus allowing high energy particles of the hard radiation belt to penetrate deep into the upper atmosphere to altitudes below a hundred kilometers (62 miles)," said Mandea.

This radiation does not influence temperatures on Earth. The particles, however, do affect technical and radio equipment and can damage electronic equipment on satellites and airplanes, said Olsen.

According to Peter Olson, a geophysics professor at Johns Hopkins University in Baltimore, Maryland, the study documents just how rapidly the flow in Earth's core is changing.